Method for fabricating substrate structure

ABSTRACT

A substrate structure has an obtuse portion formed between a side surface and a bottom surface of a substrate body. The obtuse portion includes a plurality of turning surfaces to disperse the stress of the substrate body generated in the packaging process. Therefore, the substrate body is prevented from being cracked. A method for fabricating the substrate structure and an electronic package including the substrate structure are also provided.

BACKGROUND 1. Technical Field

The disclosure relates to semiconductor packages, and, moreparticularly, to a substrate structure, an electronic package having thesubstrate structure, and a method for fabricating the substratestructure.

2. Description of Related Art

There are numerous techniques used in chip packaging, including flipchip modules, such as Chip Scale Package (CSP), Direct Chip Attached(DCA) or Multi-Chip Module (MCM), or 3D IC chip stacked modules thatstack chips in a three-dimensional manner, wherein packaging structureareas are reduced and signal transmission paths are shortened by flipchip package fabrication processes.

In flip chip package fabrication processes, since the thermal expansioncoefficients of a chip and a package substrate are quite different fromeach other, bumps on the outer periphery of the chip cannot form goodbonding with corresponding contacts on the package substrate, and may bepeeled off from the circuit substrate. As the degree of integration ofintegrated circuits increases, mismatch in thermal expansioncoefficients between the chip and the package substrate, as well as thethermal stress and warpage resulting from the mismatch, become moresevere. As a result, reliability in electrical connections between thechip and the package substrate reduces, leading to failures inreliability tests.

In order to address the above problem, an interposer made of asemiconductor substrate disposed between the chip and the packagesubstrate has been proposed. By using a semiconductor substrate made ofa material similar to the material of the chip, mismatch in thermalexpansion coefficients between the chip and the package substrate can beeliminated.

As shown in FIG. 1, a semiconductor chip 13 is provided on a ThroughSilicon Interposer (TSI) 12 via a plurality of solder bumps 130. The TSI12 has a plurality of Through Silicon Vias (TSVs) 120, and aredistribution layer (RDL) 121 electrically connecting the TSVs 120 andthe solder bumps 130. The TSI 12 is bonded onto a package substrate 11via the TSVs 120 and a plurality of conductive elements 110. Theconductive elements 110 and the solder bumps 130 are then encapsulatedwith an underfill 10′, and the semiconductor chip 13 and the TSI 12 areencapsulated by an encapsulant 10.

However, in the traditional packaging process of the semiconductorpackage 1, when temperature cycle or stress variation is encounteredduring transportation, passing through reflow oven, or drop tests, forexample, a large corner stress may be created at some regions (e.g., thecorners) of the semiconductor chip 13 and the TSI 12, causing cracks(such as cracks K in the diagram) to appear around the corners of thesemiconductor chip 13 and the TSI 12, resulting in damage of the TSI 12or the semiconductor chip 13, poor electrical connections between theTSI 12 and the semiconductor chip 13, failure in reliability tests, andeventually a poor product yield.

Moreover, the space between the semiconductor chip 13 and the TSI 12 forthe underfill 10′ becomes smaller, so the stress experienced at theedges of the semiconductor chip 13 is smaller, whereas the space betweenthe TSI 12 and the package substrate 11 for the underfill 10′ is larger,so the stress experienced at the edges of the TSI 12 is larger.Therefore, cracks (crack K shown) are more likely to occur atright-angle corners of the TSI 12, resulting in poor productreliability.

Therefore, there is an urgent need to find a solution that overcomes theaforementioned problems in the prior art.

SUMMARY

In view of the foregoing shortcomings in the prior art, the disclosureprovides a substrate structure, which may include: a substrate bodyincluding a first surface, a second surface opposite to the firstsurface, a side surface adjoining the second surface, and an obtuseportion including a plurality of turning surfaces and formed between theside surface and the first surface; and a plurality of conductive bodiesbonded to the substrate body.

The disclosure further provides a method for fabricating a substratestructure, which may include: providing a substrate module including aplurality of substrate bodies; forming a first concave portion betweenany adjacent two of the substrate bodies; forming at least one secondconcave portion in the first concave portion, the second concave portionhaving a maximum width less than a maximum width of the first concaveportion; and cutting the substrate module along the second concaveportion to separate the plurality of substrate bodies, wherein each ofthe separated substrate bodies includes a first surface, a secondsurface opposite to the first surface, a side surface adjoining thesecond surface, and an obtuse portion formed between the side surfaceand the first surface and including a plurality of turning surfacesformed by a wall of the first concave portion and a wall of the secondconcave portion.

In an embodiment, a plurality of the second concave portions are formedin the first concave portion, and the maximum widths of the secondconcave portions are reduced according to the order in which they arefabricated.

In an embodiment, the method further includes forming an encapsulatingmaterial on the substrate bodies.

In an embodiment, the substrate body is made of a semiconductormaterial.

In an embodiment, the obtuse portion is provided at a corner of thesubstrate body.

In an embodiment, the obtuse portion extends along an edge of the firstsurface.

In an embodiment, the turning surfaces are disposed adjacent to oneanother.

In an embodiment, the obtuse portion includes two or three of theturning surfaces.

In an embodiment, one of the turning surfaces adjoins the side surfaceor the first surface.

In an embodiment, the second surface and the side surface adjoinvertically.

In an embodiment, one of the conductive bodies is a circuit layer, aconductive pillar, a conductive bump or a combination thereof.

The disclosure further provides an electronic package, which mayinclude: a carrier; at least one of the above substrate structuredisposed on the carrier and electrically connected with the carrierthrough the conductive bodies; and an encapsulating material formed onthe carrier. The encapsulating material includes an underfill formedbetween the carrier and the substrate structure and/or an encapsulantformed on the carrier and encapsulating the substrate structure.

In summary, the substrate structure, the electronic package having thesubstrate structure, and the method for fabricating the substratestructure in accordance with the disclosure disperse the stressexperienced by the substrate body by forming the obtuse portionincluding the plurality of turning surfaces between the side surface andthe first surface of the substrate body. Compared to the prior art, thedisclosure eliminates the occurrences of cracks in the substrate bodyduring the packaging process, thereby increasing the product yield.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic cross-sectional view of a conventionalsemiconductor package;

FIG. 2A is a schematic partial cross-sectional view of a substratestructure in accordance with the disclosure;

FIG. 2B is a partial isometric view of FIG. 2A;

FIG. 2C is another implementation of FIG. 2B;

FIGS. 3A to 3C are schematic cross-sectional views illustrating a methodfor fabricating the substrate structure corresponding to FIG. 2A; and

FIG. 4 is a schematic cross-sectional view of an electronic package inaccordance with the disclosure.

DETAILED DESCRIPTION OF THE EMBODIMENTS

The disclosure is described by the following specific embodiments. Thosewith ordinary skills in the arts can readily understand other advantagesand functions of the disclosure after reading the disclosure of thisspecification. The disclosure may also be practiced or applied withother different implementations. Based on different contexts andapplications, the various details in this specification can be modifiedand changed without departing from the spirit of the disclosure.

It should be noted that the structures, ratios, sizes shown in thedrawings appended to this specification are to be construed inconjunction with the disclosure of this specification in order tofacilitate understanding of those skilled in the art. They are notmeant, in any ways, to limit the implementations of the disclosure, andtherefore have no substantial technical meaning. Without affecting theeffects created and objectives achieved by the disclosure, anymodifications, changes or adjustments to the structures, ratiorelationships or sizes, are to be construed as fall within the rangecovered by the technical contents disclosed herein. Meanwhile, terms,such as “above”, “first”, “second”, “third”, “a”, “one” and the like,are for illustrative purposes only, and are not meant to limit the rangeimplementable by the disclosure. Any changes or adjustments made totheir relative relationships, without modifying the substantialtechnical contents, are also to be construed as within the rangeimplementable by the disclosure.

FIGS. 2A and 2B are schematic cross-sectional views of a substratestructure 2 in accordance with the disclosure. As shown in FIG. 2A, thesubstrate structure 2 includes: a substrate body 21, and a plurality ofconductive bodies 25 bonded to the substrate body 21.

The substrate body 21 can be a semiconductor material, and includes afirst surface 21 a, a second surface 21 b opposite to the first surface21 a, and a side surface 21 c adjoining the second surface 21 b. Thesecond surface 21 b and the side surface 21 c are joined to each otherat a right angle, and an obtuse portion A is formed between the sidesurface 21 c and the first surface 21 a. In an embodiment, the obtuseportion A is defined with a plurality of (e.g., two) turning surfaces210 and 211.

In an embodiment, the substrate body 21 is, but not limited to, asilicon chip or a Through-Silicon Interposer (TSI), and the substratebody 21 is, but not limited to, in the form of a strip or singulated.

Furthermore, the substrate body 21 can be a board in any geometricshape, such as rectangle (shown in FIG. 2B), polygon, circle or etc.,and can be a symmetrical or non-symmetrical board, such that thesubstrate body 21 may assume a variety of different appearances, and thedisclosure is not limited to these.

Moreover, the obtuse portion A adjoins the first surface 21 a, withoutadjoining the second surface 21 b, and the turning surfaces 210 and 211are planar oblique faces. The turning surface 211 adjoins the sidesurface 21 c, and the turning surface 210 adjoins the first surface 21a. As shown in FIG. 2A, the turning surface 210 adjoins an edge of thefirst surface 21 a and extends to form another turning surface 211, suchthat these turning surfaces 210 and 211 are not parallel with the firstsurface 21 a and the side surface 21 c, and the angles of the turningsurfaces to adjacent surfaces are all obtuse angles. In an embodiment,the angle between the turning surface 210 and the first surface 21 a is150°, and the angle between the turning surface 211 and the side surface21 c is 153°. It can be appreciated that the turning surface 210 can bealmost at a right angle to the first surface 21 a (i.e., the turningsurface 210 is almost parallel to the side surface 21 c), and the otherturning surface 211 is almost horizontally connected thereto (i.e., theturning surface 211 is almost parallel to the first surface 21 a), thusforming a breach on the obtuse portion A.

The range of the obtuse portion A can be selected according to needs.The ranges of the turning surfaces 210 and 211 can also be selectedaccording to needs. In an embodiment, the total height H of the turningsurfaces 210 and 211 is 61.6 μm, the total width T of the turningsurfaces 210 and 211 is 50.8 μm, the height h of the turning surface 210is 16.1 μm, and the width t of the turning surface 211 is 22.5 μm. Thenumber of turning surfaces are not limited to two, and the obtuseportion A may be defined with three turning surfaces, such as turningsurfaces 210, 211, 212 shown in FIG. 2C, or four or more turningsurfaces.

The conductive bodies 25 can be a circuit layer (not shown), innerconductive pillars (not shown), conductive bumps (such as those shown inFIG. 2), or a combination of the above.

In an embodiment, each of the conductive bodies 25 includes a metalpillar 25 a and a solder material 25 b provided on the metal pillar 25a.

Referring to FIGS. 3A to 3C, schematic cross-sectional diagramsillustrating a method for fabricating the substrate structure 2 inaccordance of the disclosure are shown.

As shown in FIG. 3A, a substrate module 3 including a plurality ofsubstrate bodies 21 is provided, and a plurality of conductive bodies 25can be selectively bonded to the substrate bodies 21. At least one firstconcave portion 30 is formed on the first surfaces 21 a of the substratebodies 21. The substrate bodies 21 are arranged in an array, and thefirst concave portion 30 is formed between any two of the substratebodies 21.

In an embodiment, the substrate module 3 is, but not limited to, asilicon wafer (including or not including the conductive bodies 25), ora package structure without singulation (such as a package structureincluding an underfill 400, a first substrate 21 and a second substrate42, which will be described later, and which may include or not includethe conductive bodies 25).

As shown in FIG. 3B, at least one second concave portion 31 is formed inthe first concave portion 30, the maximum width D of the second concaveportion 31 is less than the maximum width R of the first concave portion30, and a wall 30 c of the first concave portion 30 and a wall 31 c ofthe second concave portion 31 become the turning surfaces 210 and 211,respectively.

In an embodiment, there are various ways for making the first and secondconcave portions 30 and 31, including mechanical cutting, ultrasoundpolishing, chemical-mechanical polishing (CMP), laser, water jet cutter,isotropic/anisotropic etching, dry/wet etching, or a combination of theabove processes. In the case of mechanical cutting, cutting tools withtwo or more angles can be used.

The first and second concave portions 30 and 31 can have a variety ofdifferent appearances, and are not limited to the triangularcross-sectional shapes shown in FIGS. 3A and 3B, but can be othergeometric shapes (e.g., arc, polygon, circle etc.)

Moreover, if a plurality of second concave portions 31 are formed in thefirst concave portion 30, the maximum widths D of these second concaveportions 31 decrease with the order in which they are fabricated, so asto form more turning surfaces.

Furthermore, the depths of the concave portions define the range of theobtuse portion A. It can be appreciated that the more concave portionsthat are formed (e.g., more cutters with different blade angles), themore the appearance of the obtuse portion A looks like an arc. Morespecifically, according to experiments, two or three turning surfacesmeets practical demands, and can be achieved by cutting tools.

As shown in FIG. 3C, the substrate module 3 is cut using the secondconcave portion 31 as the cutting path, thereby separating the substratebodies 21 and forming a plurality of substrate structure 2.

Accordingly, in the substrate structure 2 according to the disclosure,the obtuse portion A is formed between the side surface 21 c and thefirst surface 21 a of the substrate body 21, such that the edges of thesurface of the substrate body 21 are obtuse instead of acute, thuseliminating the issue of stress concentration due to right angles.Therefore, with the design of the turning surfaces 210 and 211 on thesubstrate structure 2 according to the disclosure, the stress createdduring subsequent packaging process can be dispersed, and stressconcentrating around corners (or other places) of the substrate body 21can be eliminated. As a result, the substrate structure 2 is less likelyto have cracks after packaging, thereby increasing the product yield.

FIG. 4 is a schematic cross-sectional view of an electronic package 4 inaccordance with the disclosure. The electronic package 4 includes: acarrier 43, a substrate structure (e.g., a first substrate 41 and/or asecond substrate 42) disposed on and electrically connected with thecarrier 43, and an encapsulating material 40 for encapsulating thesubstrate structure.

The carrier 43 can be made of a metal, ceramic or organic material, andis used as a package substrate, and the first substrate 41 and thesecond substrate 42 are semiconductor materials. The second substrate 42is used as a TSI and is placed directly on and electrically connectedwith the carrier 43, while the first substrate 41 is used as anelectronic element and is bonded to and electrically connected with thesecond substrate 42.

In an embodiment, the carrier 43 is a substrate with a core layer and acircuit structure or a coreless circuit structure such as a fan-outredistribution layer (RDL). It can be appreciated that the carrier 43can be used as, but not limited to, a carrier unit (e.g., a leadframe)for carrying other electronic elements (e.g., a chip).

In an embodiment, the first substrate 41 is an electronic element, suchas an active element, a passive element or a combination of both. Inanother embodiment, the active element can be a semiconductor chip, andthe passive element can be a resistor, a capacitor or an inductor.

In another implementation (not shown), the first substrate 41 (e.g., theelectronic element) can be directly placed on the carrier 43, withoutthe intermediate second substrate 62 (e.g., the TSI) disposed.

Moreover, the obtuse portion A including the plurality of turningsurfaces 210 and 211 can be optionally formed on the first substrate 41and/or the second substrate 42. It can be appreciated that the size ofthe first substrate 41 is very small, such that the appearance of theobtuse portion A formed thereon approximates an arc shape.

The conductive bodies 25 are bonded to the first substrate 41 and thesecond substrate 42 for electrically connecting the first substrate 41,the second substrate 42 and the carrier 43.

The encapsulating material 40 is formed on the carrier 43 to encapsulatethe first substrate 41 and the second substrate 42.

In an embodiment, the encapsulating material 40 includes an underfill400 and an encapsulant 401. The underfill 400 is formed between thefirst substrate 41 and the second substrate 42 and between the secondsubstrate 42 and the carrier 43, and the encapsulant 401 is formed onthe carrier 43 to encapsulate the underfill 400, the first substrate 41and the second substrate 42.

Accordingly, the electronic package 4 according to the disclosure allowsstress on the first substrate 41 and the second substrate 42 createdduring formation of the encapsulating material 40 to be dispersedthrough the design of the turning surfaces 210 and 211 (or the obtuseportion A), eliminating the issue of stress being concentrated at thecorners of the first substrate 41 and the second substrate 42, andpreventing cracks from occurring in the first substrate 41 and thesecond substrate 42 during the packaging process, thereby increasing theproduct yield.

Therefore, the turning surfaces 210 and 211 (or the obtuse portion A)disclosed can be located as required. For example, they can be locatedat places on the substrate body 21 where stress concentration is proneto occur during the fabrication processes of the substrate structure 2,thereby avoiding cracks to be formed on the substrate body 21. Forexample, the obtuse portion A is located at each of the corners of thesubstrate body 21, or even along the edges of the first surface 21 a,such as that shown in FIG. 2B. More specifically, during the packagingprocess, corner stress is formed from stress being concentrated at thecorners of the substrate body 21, causing large stress between thesubstrate body 21 and the encapsulating material 40, so these turningsurfaces 210 and 211 can be disposed at the corners.

In summary, the substrate structure, the electronic package having thesubstrate structure, and the method for fabricating the substratestructure in accordance with the disclosure alleviate stressconcentration and thus increases the product yield through the provisionof the turning surfaces.

The above embodiments are only used to illustrate the principles of thedisclosure, and should not be construed as to limit the disclosure inany way. The above embodiments can be modified by those with ordinaryskill in the art without departing from the scope of the disclosure asdefined in the following appended claims.

1-11. (canceled)
 12. A method for fabricating a substrate structure,comprising: providing a substrate module including a plurality ofsubstrate bodies; forming a first concave portion between any adjacenttwo of the substrate bodies; forming at least one second concave portionin the first concave portion, the second concave portion having amaximum width less than a maximum width of the first concave portion;and cutting the substrate module along the second concave portion toseparate the plurality of substrate bodies, wherein each of theseparated substrate bodies includes a first surface, a second surfaceopposite to the first surface, a side surface adjoining the secondsurface, and an obtuse portion formed between the side surface and thefirst surface and including a plurality of turning surfaces formed by awall of the first concave portion and a wall of the second concaveportion.
 13. The method of claim 12, wherein one of the obtuse portionsis provided at a corner of a corresponding one of the substrate bodies.14. The method of claim 12, wherein one of the obtuse portions extendsalong an edge of the first surface of a corresponding one of thesubstrate bodies.
 15. The method of claim 12, wherein one of the obtuseportions includes two or three of the turning surfaces.
 16. The methodof claim 12, wherein the turning surfaces are disposed adjacent to oneanother.
 17. The method of claim 12, wherein one of the turning surfacesadjoins the side surface or the first surface.
 18. The method of claim12, wherein the second surface and the side surface adjoin vertically.19. The method of claim 12, wherein the first concave portion is formedwith a plurality of the second concave portions therein, and the secondconcave portions have maximum widths reduced according to an order of afabrication process thereof.
 20. The method of claim 12, furthercomprising forming an encapsulating material on at least one of thesubstrate bodies.